MADISON, Wis. (AP) — U.S. Sen. Bernie Sanders returned to the friendly terrain of Wisconsin on Friday, promising to build a coalition that will defeat President Donald Trump as he kicked off a swing through pivotal states that are part of the Democratic “blue wall” strategy for 2020. Sanders, speaking to a crowd of about 2,400 who braved 40-degree temperatures with a stiff 20 mph wind, pledged to flip Midwestern states such as Wisconsin that Trump narrowly won in 2016. “Together, we are going to make sure that does not happen again,” Sanders said to cheers. “We’re going to win here in Wisconsin. We’re going to win in Indiana. We’re going to win in Ohio. We’re going to win in Michigan. We’re going to win in Pennsylvania and together we’re going to win this election.” Sanders spoke in a city park along the shores of a lake, just a few blocks away from the state Capitol. Those in the crowd wore ski masks, winter coats, gloves and scarves as they cheered Sanders. The independent senator from Vermont carried Wisconsin by 13 points in the Democratic primary three years ago and has been a frequent visitor since losing the nomination to Hillary Clinton. He touted his appeal to working-class and college-age voters, while fostering his network of supporters before this second run for president. “He’s the real deal,” said Sanders backer Lynn Glueck, 50, a teacher from Madison who wore a winter coat with the hood up for the rally. She said to win, Sanders needs to emphasize his “long term integrity.” “It’s not like he came up with these ideas the past two years, Glueck said. “He is not somebody who is bought and sold.” University of Wisconsin students Dylan Karls, 20, and Aaron Dwyer, 20, came from the nearby campus to check out the rally. They said they didn’t know which Democrat they will vote for yet but liked that Sanders was forcing other candidates to take more liberal positions. “I think he cares more than a lot of other politicians,” Dwyer said. “He’s a candidate people can get behind because he cares.” Democrats have made clear that their best chance at defeating Trump in 2020 is by winning back three states Trump narrowly captured: Wisconsin, Michigan and Pennsylvania. Dubbed the “blue wall” before they unexpectedly tipped to Trump, they may have supplanted Florida and Ohio as the nation’s premier presidential battlegrounds. Following the Wisconsin rally, Sanders was headed to Gary, Indiana, on Saturday. He’ll hold a rally at a community college in Warren, Michigan, later that day, and then head to Pennsylvania for an event Sunday near the University of Pittsburgh and Carnegie Mellon campuses. Then it’s off to Ohio on Monday.